Safety bed



April 8, 1952 c. c. MOLEAN ET AL 2,592,166

SAFETY BED Filed 001;. 17, 1947 2 SHEETS-SHEET 1 mmmwm COL/N C MCLEAWSQNDER H. Dav/5 FITTORNE YS April 8, 1952 c. c. MCLEAN ET AL 2,592,166

SAFETY BED Filed Oct. 17, 1947 V 2 SHEETSSHEET 2 Cou/v C McLEm/ 50/0556. DfiV/S 2! 23mm, uym' 060mm 4' Jam/mu f 7 if ATTORNEYS PatentedApr. 8, 1952 SAFETY BED Colin 0. McLean and Sander A. Davis, Chicago,

111., assign ors to Hospital Furniture, Inc., Ohicago, 111., acorporation of Illinoisv Application October 17, 1947, Serial No.780,486

3 Claims. (Cl. -63) This invention relates to a bed and more particularly to a bed which may be adjusted at any height from the normallow level of a home bed to the high position of hospital beds.

The top of the mattress of the usual home bed is about 24 inches abovethe floor. The height of a hospital bed, on the other hand, isstandardized at a height of 33 inches to raise the patient to aconvenient height for examination or treatment. It is not desirable tomaintain a bed at the higher level because of the likelihood of aserious injury resulting from a fall. A bed which may be adjusted fromone level to the other is highly desirable.

Beds which may be adjusted to a number of different heights haveheretofore relied on a series of mechanical connections spaced atintervals along the posts of a bed. The connections usually have beeneither of the familiar bayonet type or have consisted of a series ofholes in the bed posts for the reception of a pin connected to the frameof the bed. In order to change the level of beds of the type described,it is obviously necessary that the occupant of the bed be movedtherefrom while the level is being changed.

In order to facilitate the adjustments of the level of the bed, someprior structures have a rack and pinion gear mechanism with the racksecured to the posts of the bed. Here, again, the prior structures havemade it necessary to adjust the height of one end of the bed at a timethereby making it necessary for the occupant to be moved from the bedwhile it is being adjusted to the desired position. Moreover, the priorstructures have relied upon a ratchet to hold the bed in position.Unless great care is taken in the setting of the ratchet, there is astrong possibility that the ratchet will slip when weight is first puton the bed.

It is an object of this invention to provide a bed which may be adjustedat any desired level between the normal low level of a home bed and thehigh level of a hospital bed.

Another object of this invention is to provide a bed the height of whichmay be adjusted while an invalid is in the bed. j

Still another object of this invention is to provide a safety bed whichmay be of attractive appearance and in which the mechanism for"adjusting the level of the bed is concealed and guarded.

A further object of this inventionis a bed which may be adjusted at anydesired height and which will lock in place without danger of slipping.

With these and other objects in mind which will become apparent in thefollowing detailed description of the invention, this invention residesin a bed having legs slidable within the corner posts. A rack secured toeach of the legs is engaged by pinion gears in a fixed position relativeto, and rotatably connected with, the corner posts for moving the legsrelative to the corner posts. A worm gear mechanism is mechanicallylinked with the pinions to move all legs simultaneously and hold the bedat the desired level.

In the drawings:

Figure l is a perspective view of a bed constructed according to thisinvention.

Figure 2 is a horizontal sectional view illustrating the mechanismprovided for extending all of the legs of the bed simultaneously. 7

Figure 3 is a vertical sectional View of the mechanism taken alongsection line 3- 3- of Figure 2. V

Figure 4 is a vertical sectional view along the line 4-4 in Figure 2 ofthe leg and corner post structure of the bed.

Figure 5 is a schematic diagram of the electrical connections foroperating the motor for raising and lowering the bed. 7

Referring to Figure 1, the bed, indicated generally by I, is illustratedhaving a headboard 2 and a footlooard 3.. Attached to each end of theheadboard and foot'board are corner posts 4 into which legs 5 extend. Aframe, indicated generally by 6, is attached to the corner posts for thesupport of the springs and mattress of the bed. Frame 6 consists of siderails 1 extending between the head and foot boards 2 and 3 at the endsof the bed. In some instances it may be desirable to extend rails, notshown in the drawing, parallel to the head and foot boards rather thanuse the head and foot boards as" part of the frame of the bed. The termsheadboard" and footboard" are used to designate the structure at theends of the bed joining the corner posts and are not limited to thedetails of the structure illustrated.

1 Corner posts 4 have a long cavity 8 in their lower end in which thelegs 5 of the bed fit snugly but slidably. An opening 9 is provided inthe walls of cavity 8 for passage of the mechanical linkage raising andlowering the bed. The upper end of corner post 4 is drilled to iorm awell 10 in which racks, not shown, for the supportof equipment for bloodtransfusions or glucose injections, or exercisingapparatus, may beanchored. Each well is covered with a cap [I hinged at l2 to the upperend of the corner post.- v

The legs 5 are of any conventional type equipped with a caster [3 attheirlower end and fit in a telescoping manner in the cavity 8 of-tl-iecorner post 4. A rack i4 is secured to a side or the legs,

near their upper end and in alignment with the opening 9' in the cornerpost of the bed. It is preferred that the legs 5 -fit within the cornerpost [rather than have the corner post 4' slide .rotation of thespindles and In the form of the iifiention illustrated in the drawings,the frame supporting the springs and mattress consists of side rails land head and foot boards 2 and 3. The frame serves as a support forpinion gears l6 which engage the rack l4, as hereinafter described, andthe mechanism for driving the pinion gears. The frame is securely fixedto either the corner post or headboard and footboard of the bed andremains in fixed relation to the corner posts as the leg slides withinthe corner post. As illustrated in Figure 2, an electric motor I! issecured to base l8 attached to. the frame 6 of the bed.

The motor I1 is thoroughly insulated from the bed and is preferablycompletely enclosed. In the drawings the shaft 19 of the motor is joinedby means of couplings 20 and 2! directly to a shaft 22 extending thefull length of the bed. In some instances it may be desirable to installa speed reducer between the shaft l9 of the motor and the shaft 22 toreduce the rate of rotation of shaft 22 and, as a result, the rate ofmovement of the bed.

Shaft 22, which extends substantially the full length of the bed, issupported at its ends by pillow blocks 23 and 24. By locating motor I!near the middle of the bed, the bearings of the motor are made to serveas support for the shaft 22. Worm gears 25 and 26 are secured to shaft22 near each end thereof for transmitting power from the shaft;

Extending perpendicularly to shaft 22 at each end of the bed arespindles 21 and 28. The spindles 21 and 28 are rotatably supported belowthe shaft 22 by pillow blocks 29 attached to the corner posts 4 of thebed. Keyed to the spindles 21 and 28 are worm wheels 30 and 3| whichengage the worm gears 25 and 26, respectively,'to rotate the spindles.The speed reduction of the worm gear and worm wheel assembly is employedto adjust the rate of elevation of the bed to the desired speed. Byproper design of the worm gear and worm wheel linkage, the necessity fora speed reducer between the shaft of the motor -and shaft 22 isobviated. The pinion gears l6 mentioned in connection with rack l4 arekeyed to the spindles 21 and 28 near their ends. The

pinion gears l6 extend through the openings 9 to engage the racks l4attached to the legs of the bed.

The worm gear and worm wheel mechanism for rotating the pinion gears [6provides a means for locking the bed in positionat the height itoccupies when the motor is stopped. The weight of the bed and the personin the bed urges the pinion gears l6 downward and tends to turn thepinion gears l6 backwards on the spindles when the motor is stopped. Theworm wheels 30 and 3| engage the worm gears 25 and 26 to prevent piniongears l6 and hold the bed firmly in place.

It will be noticed that all of the pinion gears I6 are drivensimultaneously to maintain the bed in a horizontal condition as it isbeing raised or lowered. The bed may be raised orlowered ,with perfectsafety while occupied;

Referring to Figure 5, a limit switch for the control of the operationof the motor is illustrated schematically. Shaft 22 is threaded at .32for the reception of a nut 33. -An arm 34 i s complete the circuit tothe motor I! through lines 38 and 39.

In the electrical circuit through the motor I! is a reversible switch 40indicated by a conventional electrical symbol. Switch 40 is preferablylocated on the headboard of the bed as indicated in Figure 1. Reversibleswitch 40 is normally in an open position preventing current fromflowing to the motor I1. It is necessary that switch 40 be held in theclosed position to operate the motor. Power for operating the motor isreceived through lines 4| and 42 which are connected to a suitableoutlet, not shown.

If the bed is at the lower position of a normal home bed and it isdesired to raise it to the elevated position of a hospital'bed, it ismerely necessary to depress the proper button of reversible switch 40.The closed switch allows the electrical current to flow to the motorwhich then rotates shaft 22. Shaft 22 in turn drives spindles 21 and 28and the pinion gear 16 simultaneously. Pinion gears l6 engage the racksl4 in each of the legs of the bed and cause the legs to move within thecavity 8 of the corner post 4. It will be noted that the spindles 21 and28, and, accordingly, pinion gears l 6 are attached securely to theframe of the bed which i turn is rigidly connected with the corner post4. As a result, spindle I6 will remain in a fixed position relative tothe corner post 4 and its rotation will cause the rack l4 and legs 5 tomove relative to the corner post.

As rotation of shaft 22 continues, the nut 33 will travel along thethreaded portion 32 of the shaft until arm 34 engages the closedswitches 31, for example, and opens the electrical circuit. The motor I!then stops and the bed is held in position by the worm wheel and wormgear arrangement.

It will be noted that ordinarily both switches 36 and 31 are closed andthat only one of the switches will be open at one time. The travelingnut 33 and arm 34 arrangement will accordingly always condition theelectrical circuit for the movement of the bed in a direction oppositeits last movement. Of course, if the bed is not elevated sufficiently totrip switch 31, both switches 36 and 31 will be closed and the bed maybe either raised or lowered by depressing the proper button in switch40. i

In some instances it is desirable that the shaft 22 be extended pastpillow block 24 and pass through the footboard 3 for detachableconnection with a crank 43. The bed may then be operated when a suitablesource of electric power is not available.

The bed herein described may be readily raised or lowered to the desiredheight while the bed is occupied. The mechanism of this invention altersthe effective length of the leg of the bed simultaneously to maintainthe bed in a horizontal position as its height is being changed.Moreover, the mechanism for altering the effective length of the legs isenclosed and concealed to prevent entanglement with the bed clothes andto provide a bed of pleasing appearance.

A bed constructedaccording -to this invention has been described hereinwith reference to a particular structure. It is to be understood thatthe concept of this invention is not limited to the details of thestructure described, but is defined by the appended claims.

We claim:

1. A hospital safety bed comprising a mattress supporting frame, tubularcorner posts secured-to the corners of the mattress supportingframe; aleg slidable in each of the corner posts, a 'r'aelggon each leg, a motorsecured to the frame, a shaft driven by the motor, said shaft extendingthe length of the bed and rotatably supported by the frame, a spindlerotatably supported at each end of the bed, a pinion gear on each end ofthe spindles, a worm gear on each end of the shaft engaging a worm wheelon the spindles, an opening in each of the corner posts permitting-thepinion gears to engage the racks On the.., leg s of the bed, switchmeans for closing a circuit to operate the motor to raise and lower themattress supporting frame, said shaft having a threaded section alongits length, and limiting means travelling on the threaded sectionadapted to open the switch means to limit movement of .the bed, saidlimiting means stopping movement of the bed at the treatment level whenthe bed is moving upward and the normal bed height when the bed ismoving downward.

2. A hospital safety bed adjustable to an upper treatment position and alower safety position comprising a single mattress supporting frame,corner posts secured to the frame, a leg slidable within each of thecorner posts, means for 'mov ing all of the legs relatively to thecorner posts simultaneously, said means including an electric motormounted on the frame adapted to move therewith, a shaft rotatablysupported from the frame and driven by said motor, a rack secured toeach of the legs, pinion gears rotatably suD- ported from the frameengaging the racks, worm gears on the shaft adapted to drive the piniongears and move the legs relatively to the corner posts, said motoradapted to turn in either direction to move the legs into and out of thecorner posts, and limit switches operated by said shaft adapted to breakthe circuit to the motor to stop the movement of the bed at thetreatment position as the bed moves upward and at the safety position asthe bed mbves downward.

3. A hospital safety bed adjustable to an upper treatment position and alower safety position comprising a single mattress supporting frame,corner posts secured to the frame, a leg slidable within each of thecorner posts, means for moving all of the legs relatively to the cornerposts simultaneously, said means including an electric motor mounted onthe frame, a rack mounted on each of the legs, pinion gears mounted onthe frame and engaging the racks'to move the legs relative to the cornerposts, and means driven by the motor for turning thejpinion gears tomove the legs in the corner posts simultaneously, said motor adapted toturn in either direction to move the legs into and out of the cornerposts, and limit switches operated bythe motor adapted to break thecircuit to the motor to stop the movement of the bed at the treatmentposition as the bed moves upward and at the safety position as the bedmoves downward.

COLIN c. McLEAN. SANDER A; gmwrs.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,228,434 Hedberg June 5, 19171,265,257 Schellinger May 7, 1918 1,366,517 Brown June 25. 19212,522,759 Lindquist Sept. 19, 1950 2,523,076 Sweetland Sept. 19, 1950

